The writer David Leadbeater has struck gold with his self-published archaeological thriller, The Relic Hunters, scooping up the first Amazon Kindle Storyteller award.

Leadbeater pronounced it “a dream come true” to win the £20,000 award, which is open to writers who produce their books using the online retailer’s Kindle Direct Publishing platform.

According to the author, The Relic Hunters is “like a Hollywood blockbuster movie on paper”. It tells the story of relic smuggler Guy Bodie, rescued by the CIA from a hellish Mexican prison to help them discover what has happened to one of the seven ancient wonders of the world.

Amazon said it received thousands of entries for the award, which were then whittled down to a shortlist of six using a mixture of sales data, user ratings and customer reviews. The eclectic lineup also included Jono Dunnett’s memoir about the first solo round-Britain windsurf, Long Standing Ambition, and Jade Winters’ lesbian romance Lost in You.

The shopping site then employed a more traditional approach, with a panel of judges including the actor Lily Cole, authors Rachel Abbott and Orna Ross and members of the Amazon books team eventually eventually settling on Leadbeater’s entry.

Leadbeater said he had been publishing his work online for about five years.

“The first book I published on the Kindle took about six months to start to sell in good numbers,” he said. “I was still working at a builders’ merchant’s at the time, and I wrote my first four books of an evening.”

After four novels, Leadbeater continued, sales were good enough for him to write full-time. Now that he has published more than 20 thrillers, he estimated that he had now sold more than 750,000 ebooks. He added that although he was approached by publishers early on, so far he has resisted their offers. “I prefer to go it alone,” he said, “to be my own boss – there’s so much freedom.”

Publishers, however, continue to eye up Kindle’s successful authors. “Absolutely we look at them,” said Sam Eades, editor at Orion imprint Trapeze. “An editor will always receive submissions from agents, but just as important now … is being on Amazon and watching that Kindle chart – seeing what’s bubbling up out there. It’s a huge part of our jobs now, and a lot of the snobbery that used to exist has disappeared. What these writers have is a track record – customer reviews are incredibly important, and they have an existing fan base. So we’re all looking at the charts, and at the prize, seeing it as a talent pool.”

The prize also includes a dedicated marketing campaign, the chance to have the winning book translated and access to mentoring.